Means for applying heat to the water tubes of boilers



March 12, 1940.

T. A. SOLBERG MEANS FOR APPLYING HEAT TO THE WATER TUBES OF BOILERS Filed Jan. 31, 1938 2 Sheets-Sheet 1 O O OO O O O O OO O O O O O O 000 O O K 3 o 00 a Q E o o yo OQNIO o Q o O -O 0 0 O O 0 0 O O o O O O O OO\O O O O O o 0 0 0 0 0R 0 O o 0 O 0 0 O 0 0 0 0 o 0 o o o o o 0 O INVENTOR M. 50L 55m ATTORNEY March 12, 1940. T. A. SOLBERG 2,192,941

MEANS FOR APPLYING HEAT TO THE WATER TUBES OF BOILERS Filed Jan. 31, 1938 2 Sheets-Sheet 2 91/, IVL 2; 0000000000 0000000000000 000000000 y; 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 7 f/ 03: 0 0 0 0 0 0 0 0 0 0 0 0 0 0 {Z 55 34 0 0 0 0 0 0 0 0 0 '0 0 2 g 35 0 0 0 0 0 0 0 0 0 0 0 0 6 x; 0 0 0 0 o 0 0 0 0 0 0 0 0 0 3M 0 0 0 0. 0 0 0 39 0 0 0 0 0 0 0 5/ 0 0 0 0 0 0 0 0 0 0 0 0 0 0 4, 40; 0 0 0 0 0 0 ,0 0 0 0 0 0 0 0 m l, a 30 00000000000000000000 fly, 00000000000000000000 *4 00000000000000000000 v y OOOOOOOOOOOOOOOOOOOO 4 OOOOOOOOOOOOOOOOOOO OOOOOOOOOOOOOOOOOOOO OOOOOOOOOOOOOOOO OOOOOOOOOOOOOOOOO OOOOOOOOOOOOOOOOO OOOOOOOOOOOOOOOO OOOOOOOOOOOOOOOO OOOOOOOOOOOOOOOO OOOOOOOOGOOOOO OOOOOOOOOOOOOOO' :2; 0 0 0 0 0 0 0 0 0 0 0 0 0 0 42? v fl F G 5 INVENTOR 77A L BY ATTORNEY Patented Mar. 12, 1940 UNITED STATES MEANS FOR APPLYING HEAT TO THE WATER TUBES F BOILERS Thorvald A. Solberg, United States Navy Application January 31, 1938, Serial No. 187,875

7 Claims.

(Granted under the act of March 3, 1883, as amended April 30, 1928; 370 0. G. 757) This invention relates to a method and means for applying heatto the water tubes of boilers. Essentially, all of the heat of combustion which heats the water until the same may be transposed 5 into steam is applied by conduction through the metal walls which confine the water and/or steam, and which walls for highest eiiiciency usually are in the form of a plurality of spaced apart tubes. According to long teachings and practices in this art the great volume of the combustion heat is applied to such walls or tubes by convection, and very, little of such volume has been applied to such walls or tubes by means of radiation from the combusting fuel to such walls or tubes. Furthermore, such teachings and practice inculcate and proceed upon the theory that in the conventional type of Water tube boiler a substantial increase in the rate at which steam is made may be obtained only by increasing the number of the water tubes and by accelerating the velocity at which the hot combustion gases pass over such walls or between the Water tubes.

The primary purpose of this invention is to accomplish the transfer of heat to water in a boiler for the purpose of making steam, and to do it in such a way as will result in the. use of a lesser number of tubes than that used in the conventional boiler. Primarily, therefore, the

amount of water evaporated per square foot of heating surface will be increased over that obtained in conventional type boilers, and thereby will result in boilers having less weight, smaller size, and consequently less maintenance cost.

A further object of the invention, resulting from the above, isto require less space for the combustion of fuel, and to provide a boiler having a higher operating efiiciency than that of other similar designs. The objects of this invention are realized by providing the arrangement .40 of the boiler heating surfaces so that a larger .50 nest in patterns which essentially form one or more arches, or tapering projections, which extend from the normal tube nest toward the furnace or combustion chamber of the boiler. These designs or patterns, in addition to increasing the :55 amount of surface subjected to radiant heat inof tubes to the next.

corporated in the usual, type of boiler, furthermore are designed in such a way as to more evenly distribute the mass flow of the hot gases through the tube nest. The design of these patterns also is such that the radiant heat may penetrate further into the body of the tube bank than in the conventional type of boiler. A further and equally important object of this invention is to improve the transfer of heat from the hot gases to the boiler tubes by convection in those areas of the boiler where all heat transfer occurs in this manner, namely, in the body of the tube bank, which is not exposed to radiant heat energy. This object is accomplished by arranging the tube patterns in those sections of 15 the boiler so that the areas available for gas passage become progressively less as gases proceed through the boiler from the furnace to the stack. The purpose of this arrangement is to provide a gradually decreasing area to compensate for the gradual decrease in volume of the gases of combustion, which decrease in volume is incident to the gradual decrease in temperature of these gases as their heat is removed in passing from one row This feature further re- 25 sults in a diminution of the amount of heating surfacerequired in the convection portions of the boiler, inasmuch as the consequent higher average gas velocity through this portion of the tube bank, as compared with that of conventional boilers, results in a greater amount of heat transfer. It further should be noted that the design of tube pattern for the convection portions of the boiler is such as to provide a more even distribution of the mass flow of the gases of combustion which results in all portions of the boiler doing the same amount'of work.,

The invention herein described is applicable not only to boilers being newly designed, but in many cases is equally applicable to boilers already built 40 and in use, which boilers could be improved by removing some tubes and thereby modifying the tube patterns, as shown for example in Figures 3 and 4 of the drawings.

With the foregoing and other objects in view, the invention consists in the construction, combination and arrangement of parts hereinafter described, and illustrated in the drawings, in which, ,50

Fig. 1 is a diagrammatic sectional View of a tube nest arrangement accordingto this invention.

Fig. 2 is a cross-section of an individual boiler tube. .5

Fig. 3 is a diagrammatic sectional view of another tube nest embodying this invention.

Fig. 4 is a diagrammatic sectional view of still another tube nest in accordance with this invention, and r Fig. 5 is a diagrammatic sectional view showing that part of the tube nest receiving its heat by convection, showing the decreasing spacing between the tubes.

There is shown at H? the furnace walls with the customary refractory lining H, between which are placed the boiler tubes l2 above the fire bed and grates (not shown).

As shown in Fig. l, in accordance with this invention, the number of tubes increase progressively in an upward direction from the fire bed. The tubes are also arranged so that the maximum number of tubes are exposed to radiation both from the fire bed and from the refractory lining H. To efiect this, there is provided outermost curved vertical rows M commencing adjacent the lining i i and curving inwardly. Spaced from this row is a next inner curved row 15 containing a lesser number of tubes, and spaced therefrom is a next inner row it with a still lesser number of tubes, followed by succeeding rows W and 18, it being observed that the lowermost tube of each succeeding row is further from the fire bed than that of the prior row.

Next to this group of five, more or less, successively shorter curved rows i l to It comes a cluster of tubes in the form of a spearhead and consisting of two rows is and 20, curved away from each other, the base of the spearhead being formed by a diamond shaped group 2i. Next to the spearhead rows l9 and 20 comes another group of curved rows 22, 23, M and 25, each row having successively less tubes. A center cluster or spearhead or rows 26 and 2'! with a diamond shaped group 28 therein joins the tubes extending symmetrically towards the other wall of the furnace.

Inward from the tubes of rows It to 28, inclusive, and in symmetrical continuation thereof isthe row of tubes 29. Beyond the row of tubes 29 is a row of tubes 3b, in which the tubes are located in spaced pairs. A similar row of tubes 3| thereabove has its pairs located partly above the spaces between the pairs in row of tubes 30. Next beyond comes an indefinite number of rows of tubes 32, sufiicient in number to absorb all the efficient heat carried by the combustion gases on the way to the chimney.

With the above arrangement, it will be apparent that the maximum number of tubes are exposed to the radiant heat from the fire bed and from the refractory linings H, as well as the reradiation from the hottest tubes nearest the fire bed, and further, that this arrangement also takes advantage of the maximum convection of the combustion gases, for the variation in the spaces between the tubes also provides decreasing gas path area as the gases progressively cool and contract as they give up their heat to the successive tubes in the path of the combustion gases through the boiler.

In Figs. 3 and 4, there are shown two arrangements embodying this invention as applied to already existing boiler tube patterns. In conventional patterns, the tubes are in closely spaced staggered rows. By sacrificing certain tubes, some convection efficiency may be'lost, but such loss, if any, is more than compensated by the great increase in radiant heat absorbing efficiency, as well as increased convection absorbing eliciency resulting from increased velocity of the combustion gases through the tube nest. In conventional patterns as the gases cool and contract in passing through the nest the efficiency of heat absorption is progressively lowered by the reduction in gas velocity.

In Fig. 3, the tubes 30 of the two lowermost rows are spaced substantially apart, by omitting every second and third tube, while at the center, several additional tubes are omitted. The next inner row of tubes 3! has the outermost tube omitted, thus placing this row of tubes 3| in staggered relation to the tubes of the row below. The same principle is followed for the next successive rows of tubes 32, 33 and 34, while rows of tubes 35, 36 and 37 have tubes commencing more closely to the lining H as shown, but also have at least every second and third tube omitted. The two topmost rows of tubes 38 may be conventionally positioned. At the center, a heartshaped recess 39 is provided by omitting such additional tubes as necessary. The omission of the tubes, as thus described, provides increased surfaces which are exposed to radiation from the furnace as Well as gas paths or lanes speeding up the velocity of the combustion gases and equalizing their flow therethrough.

In Fig. 4, the principles of this invention have been applied to a conventional pattern by omitting sufficient tubes in the lowermost three rows of tubes to provide triangular spearheaded clusters d6.

, In Fig. 5, the principles of this invention are carried out by placing the tubes 4! in the lowermost row a substantial distance apart, and gradually decreasing both the horizontal and the vertical spacing of the tubes from the bottom to the top.

Other modifications and changes in the proportions and arrangements of the parts may be made by those skilled in the art without departing from the nature of the invention, within the scope of what is hereinafter claimed.

The invention described herein may be manufactured and used by or for the Government of the United States of America for governmental purposes without the payment of any royalties thereon or therefor.

Having thus set forth and disclosed the nature of this invention, what is claimed is:

l. A boiler tube pattern consisting of a plurality of rows of tubes, the tubes in successively ascending rows being spaced more closely together to provide gas lanes therethrough of gradually decreasing area, the gas lanes curving in the direction of the center of the pattern.

2. A boiler tube pattern consisting of a plurality of rows of tubes, the tubes in successively ascending rows being spaced more closely together to provide gas lanes therethrough of gradually decreasing area, the gas lanes leading in the direction of the center of the pattern to thereby provide a maximum area of tube surface exposed to radiant energy, and to counteract the otherwise decreasing velocity of the gases as they contract in giving up their energy to the lower tubes.

3. A boiler tube pattern consisting of 3, p111.

rality of rows of tubes of substantially equal.

dug rows, thus providing a maximum amount of tube area exposed to radiant energy and also gas lanes of gradually decreasing area through, the tubes counteracting the decreasing velocity of the cooling, contracting gases passing therethrough. i

4. A boiler tube pattern consisting of a plurality of rows of tubes, the number of tubes in successively ascending rows gradually increasing to a maximum, the gas lanes curving and tapering in the direction of the center 01 the pattern.

5. A boiler tube pattern consisting of a plurality of rows of tubes, the number of tubes in successively ascending rows gradually increasing to a maximum, the gas lanes curving and tapering in the direction of the center of the pattern to thereby provide a maximum area of tube surface exposed to radiant energy, and to coun- 20 teract the otherwise decreasing velocity of the gases as they contract in giving up their energy to the lower tubes.

6. A boiler tube pattern consisting of a plurality of rows of tubes, the tubes in successively ascending rows being spaced more closely together toprovide curved gas lanes therethrou'gh of gradually decreasing area, whereby the draft loss through the banks will be a minimum and the heat absorption from the combustion and combustion productswill be a maximum,

7. A boiler tube pattern consisting of a plu- 'rality of rows of tubes, the tubes in successively ascending rows being spaced more closely together to provide curved gas lanes therethrough of gradually decreasing area, whereby combined heat absorption from radiation and convection will be a maximum with the minimum possible number of tubes and the minimum possible heat absorbing surface.

THORVALD A. SOLBERG. 

